04Password strength meter

<main class="stage">
  <div class="pw-card is-demo">
    <label class="pw-card__label" for="pw">Password</label>
    <input class="pw-input" id="pw" type="password" placeholder="Type a password">
    <div class="pw-meter">
      <span class="pw-meter__fill"></span>
    </div>
    <p class="pw-status" aria-live="polite">
      <span class="pw-status__text pw-status__text--weak">Weak</span>
      <span class="pw-status__text pw-status__text--medium">Medium</span>
      <span class="pw-status__text pw-status__text--strong">Strong</span>
    </p>
  </div>
</main>

@use "../../../../site/static/demo-tokens" as *;

$duration: $dur-base;                                  // 막대 너비·색이 바뀌는 시간
$easing: $ease-out;
$color: $error;                                        // 약함 색 기준값

@include stage($stage-paper);

.pw-card {
  width: min(210px, 80vw);
  display: flex;
  flex-direction: column;
  gap: $sp-1;
}
.pw-card__label { font-size: 12px; color: #6b6455; font-family: inherit; }
.pw-input {
  box-sizing: border-box;
  width: 100%;
  padding: $sp-2 $sp-3;
  border: 1.5px solid #d8d2c4;
  border-radius: $r-sm;
  font-size: 13px;
  font-family: inherit;
  color: $stage-ink;
  margin-bottom: $sp-2;
  &:focus { outline: none; border-color: $subject-blue; }
}
.pw-meter {
  height: 6px;
  border-radius: $r-xs;
  background: #e6e2d8;
  overflow: hidden;
}
.pw-meter__fill {
  display: block;
  height: 100%;
  width: 0%;
  background: $color;
  border-radius: $r-xs;
  transition: width $duration $easing, background-color $duration $easing;
}
.pw-status {
  position: relative;
  height: 14px;
  margin: $sp-1 0 0;
}
.pw-status__text {
  position: absolute;
  left: 0; top: 0;
  font-size: 11px;
  font-weight: 700;
  font-family: inherit;
  opacity: 0;
  transition: opacity $duration $easing;
}
.pw-status__text--weak   { color: $error; }
.pw-status__text--medium { color: #9c7c4d; }
.pw-status__text--strong { color: #51a474; }

.pw-card.is-demo .pw-meter__fill { animation: fill-cycle $dur-loop $easing infinite; }
.pw-card.is-demo .pw-status__text--weak   { animation: show-weak $dur-loop $easing infinite; }
.pw-card.is-demo .pw-status__text--medium { animation: show-medium $dur-loop $easing infinite; }
.pw-card.is-demo .pw-status__text--strong { animation: show-strong $dur-loop $easing infinite; }

@keyframes fill-cycle {
  0%, 5%    { width: 0%; background: $color; }
  30%       { width: 35%; background: $color; }
  55%       { width: 65%; background: #c8af8f; }
  80%, 100% { width: 100%; background: #51a474; }
}
@keyframes show-weak   { 0%, 5% { opacity: 0; } 12%, 45% { opacity: 1; } 55%, 100% { opacity: 0; } }
@keyframes show-medium { 0%, 50% { opacity: 0; } 58%, 70% { opacity: 1; } 78%, 100% { opacity: 0; } }
@keyframes show-strong { 0%, 75% { opacity: 0; } 83%, 100% { opacity: 1; } }

@media (prefers-reduced-motion: reduce) {
  .pw-meter__fill, .pw-status__text { transition: none; }
  .pw-card.is-demo .pw-meter__fill,
  .pw-card.is-demo .pw-status__text--weak,
  .pw-card.is-demo .pw-status__text--medium,
  .pw-card.is-demo .pw-status__text--strong { animation: none; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.pw-card {
  width: min(210px, 80vw);
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.pw-card__label {
  font-size: 12px;
  color: #6b6455;
  font-family: inherit;
}

.pw-input {
  box-sizing: border-box;
  width: 100%;
  padding: 8px 12px;
  border: 1.5px solid #d8d2c4;
  border-radius: 8px;
  font-size: 13px;
  font-family: inherit;
  color: #17141a;
  margin-bottom: 8px;
}
.pw-input:focus {
  outline: none;
  border-color: #2f6df6;
}

.pw-meter {
  height: 6px;
  border-radius: 4px;
  background: #e6e2d8;
  overflow: hidden;
}

.pw-meter__fill {
  display: block;
  height: 100%;
  width: 0%;
  background: #c2361a;
  border-radius: 4px;
  transition: width 300ms ease-out, background-color 300ms ease-out;
}

.pw-status {
  position: relative;
  height: 14px;
  margin: 4px 0 0;
}

.pw-status__text {
  position: absolute;
  left: 0;
  top: 0;
  font-size: 11px;
  font-weight: 700;
  font-family: inherit;
  opacity: 0;
  transition: opacity 300ms ease-out;
}

.pw-status__text--weak {
  color: #c2361a;
}

.pw-status__text--medium {
  color: #9c7c4d;
}

.pw-status__text--strong {
  color: #51a474;
}

.pw-card.is-demo .pw-meter__fill {
  animation: fill-cycle 2s ease-out infinite;
}

.pw-card.is-demo .pw-status__text--weak {
  animation: show-weak 2s ease-out infinite;
}

.pw-card.is-demo .pw-status__text--medium {
  animation: show-medium 2s ease-out infinite;
}

.pw-card.is-demo .pw-status__text--strong {
  animation: show-strong 2s ease-out infinite;
}

@keyframes fill-cycle {
  0%, 5% {
    width: 0%;
    background: #c2361a;
  }
  30% {
    width: 35%;
    background: #c2361a;
  }
  55% {
    width: 65%;
    background: #c8af8f;
  }
  80%, 100% {
    width: 100%;
    background: #51a474;
  }
}
@keyframes show-weak {
  0%, 5% {
    opacity: 0;
  }
  12%, 45% {
    opacity: 1;
  }
  55%, 100% {
    opacity: 0;
  }
}
@keyframes show-medium {
  0%, 50% {
    opacity: 0;
  }
  58%, 70% {
    opacity: 1;
  }
  78%, 100% {
    opacity: 0;
  }
}
@keyframes show-strong {
  0%, 75% {
    opacity: 0;
  }
  83%, 100% {
    opacity: 1;
  }
}
@media (prefers-reduced-motion: reduce) {
  .pw-meter__fill, .pw-status__text {
    transition: none;
  }
  .pw-card.is-demo .pw-meter__fill,
  .pw-card.is-demo .pw-status__text--weak,
  .pw-card.is-demo .pw-status__text--medium,
  .pw-card.is-demo .pw-status__text--strong {
    animation: none;
  }
}

var inp=document.getElementById('pw'),
    fill=document.querySelector('.pw-meter__fill'),
    card=document.querySelector('.pw-card');
inp.addEventListener('input',function(){
  card.classList.remove('is-demo');
  var v=inp.value, s=0;
  if(v.length>=6)s++;
  if(/[a-z]/.test(v)&&/[A-Z]/.test(v))s++;
  if(/[0-9]/.test(v))s++;
  if(/[^A-Za-z0-9]/.test(v))s++;
  var pct=v.length?[15,40,70,100,100][s]:0;
  var col=['#b27062','#b27062','#c8af8f','#51a474','#51a474'][s];
  fill.style.width=pct+'%'; fill.style.background=col;
});

import { useMemo, useState, type ChangeEvent, type CSSProperties } from "react";
import styles from "./PasswordStrengthMeter.module.scss";

export type PasswordStrengthMeterProps = {
  /** 막대 너비·색이 바뀌는 시간 (기본 300ms) */
  duration?: number;
  easing?: string;
};

const LEVELS = ["", "Weak", "Weak", "Medium", "Strong", "Strong"];
const COLORS = ["#e6e2d8", "#c2361a", "#c2361a", "#ff9d1f", "#1f9d55", "#1f9d55"];
const WIDTHS = [0, 15, 15, 40, 70, 100];

function score(v: string) {
  let s = 0;
  if (v.length >= 6) s++;
  if (/[a-z]/.test(v) && /[A-Z]/.test(v)) s++;
  if (/[0-9]/.test(v)) s++;
  if (/[^A-Za-z0-9]/.test(v)) s++;
  return v.length ? s + 1 : 0;
}

/** input 이벤트마다 길이·문자 조합을 다시 계산해 막대 너비·색·라벨을 갱신한다 */
export default function PasswordStrengthMeter({ duration = 300, easing = "ease-out" }: PasswordStrengthMeterProps) {
  const [value, setValue] = useState("");
  const s = useMemo(() => score(value), [value]);
  const style = { "--duration": `${duration}ms`, "--easing": easing } as CSSProperties;
  const onChange = (e: ChangeEvent<HTMLInputElement>) => setValue(e.target.value);
  return (
    <div className={styles.card} style={style}>
      <label className={styles.label} htmlFor="pw-react">Password</label>
      <input className={styles.input} id="pw-react" type="password" value={value} onChange={onChange} placeholder="Type a password" />
      <div className={styles.meter}>
        <span className={styles.fill} style={{ width: `${WIDTHS[s]}%`, background: COLORS[s] }} />
      </div>
      <p className={styles.status} aria-live="polite" style={{ color: COLORS[s] }}>{LEVELS[s]}</p>
    </div>
  );
}